Python Programs for Printing Patterns
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Python Programs for Printing Patterns

Python Programs for Creating Patterns with Loops

Patterns can be created using nested loops, where the outer loop controls the number of rows and the inner loop controls the content of each row. Below are some common examples of pattern programs:

1. Right-Angled Triangle

Pattern:

*
**
***
****
*****

rows = 5
for i in range(1, rows + 1):
    print("*" * i)

Explanation:

  • Outer loop (for i) runs for each row.
  • The * symbol is repeated i times for each row.

2. Inverted Right-Angled Triangle

Pattern:

*****
****
***
**
*

rows = 5
for i in range(rows, 0, -1):
    print("*" * i)

Explanation:

  • Outer loop runs from rows down to 1.
  • The * symbol is repeated i times for each row.

3. Pyramid

Pattern:

    *
   ***
  *****
 *******
*********

rows = 5
for i in range(1, rows + 1):
    print(" " * (rows - i) + "*" * (2 * i - 1))

Explanation:

  • rows - i spaces are printed before the stars for alignment.
  • 2 * i - 1 stars are printed in each row to form the pyramid shape.

4. Inverted Pyramid

Pattern:

*********
 *******
  *****
   ***
    *

rows = 5
for i in range(rows, 0, -1):
    print(" " * (rows - i) + "*" * (2 * i - 1))

Explanation:

  • Similar to the pyramid but starts with the widest row and decreases.

5. Diamond

Pattern:

    *
   ***
  *****
 *******
*********
 *******
  *****
   ***
    *

rows = 5
# Upper part
for i in range(1, rows + 1):
    print(" " * (rows - i) + "*" * (2 * i - 1))
# Lower part
for i in range(rows - 1, 0, -1):
    print(" " * (rows - i) + "*" * (2 * i - 1))

Explanation:

  • Combines the pyramid and inverted pyramid patterns.

6. Number Triangle

Pattern:

1
12
123
1234
12345

rows = 5
for i in range(1, rows + 1):
    for j in range(1, i + 1):
        print(j, end="")
    print()

Explanation:

  • Outer loop controls rows.
  • Inner loop (for j) prints numbers from 1 to i.

7. Floyd’s Triangle

Pattern:

1
2 3
4 5 6
7 8 9 10
11 12 13 14 15

rows = 5
num = 1
for i in range(1, rows + 1):
    for j in range(1, i + 1):
        print(num, end=" ")
        num += 1
    print()

Explanation:

  • A running counter (num) is printed and incremented for each number.

8. Pascal’s Triangle

Pattern:

      1
     1 1
    1 2 1
   1 3 3 1
  1 4 6 4 1

rows = 5
for i in range(rows):
    print(" " * (rows - i), end="")
    num = 1
    for j in range(i + 1):
        print(num, end=" ")
        num = num * (i - j) // (j + 1)  # Calculate next number
    print()

Explanation:

  • Uses a mathematical formula to compute the numbers in each row.

9. Hollow Square

Pattern:

*****
*   *
*   *
*   *
*****

size = 5
for i in range(size):
    if i == 0 or i == size - 1:
        print("*" * size)  # Print full row for the first and last row
    else:
        print("*" + " " * (size - 2) + "*")  # Print hollow row

Explanation:

  • Outer loop controls rows.
  • Prints * with spaces for hollow rows.

10. Hollow Pyramid

Pattern:

    *
   * *
  *   *
 *     *
*********

rows = 5
for i in range(1, rows + 1):
    if i == rows:
        print("*" * (2 * rows - 1))  # Full row at the base
    else:
        print(" " * (rows - i) + "*" + " " * (2 * i - 3) + ("*" if i > 1 else ""))

Explanation:

  • The base row is full of stars.
  • For other rows, spaces are printed in the middle to make it hollow.
Python Programs for Printing Patterns

Summary

These examples showcase how nested loops work together to form various shapes and patterns. Modify the number of rows or the inner logic to create custom patterns!

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